[Public WebGL] Re: [Public WebGL] Re: [Public WebGL] Effects of Completeness on Texture Image Specification

[Benoit Jacob <bjacob@mozilla.com>]

----- Original Message -----
> On 2010/08/13 12:35, Benoit Jacob wrote:
> > ...
> > The GL ES 2.0.24 says, in section 3.8.2, that a NPOT mipmapped
> > texture should be rendered as if it were opaque black.
> Section 3.8.2 is talking about fragment shader behavior in the event
> of
> sampling improperly specified textures.
> > (Even though such a NPOT mipmapped texture can still be "complete"
> > in the sense of section 3.7.10).
> >
> > I can't see where in the spec it is said that such a texture
> > creation call should generate an error?
> The test you mentioned is not creating a texture, it is attempting to
> copy to the level 1 texture image of an NPOT texture.

Right, right, sorry for the imprecise phrasing.

> 
> Section 3.7.1 says glTexImage2D returns INVALID_VALUE if level > 0 for
> NPOT textures.

Thanks, I had missed that (in my defense, section 3.7.1 is long and it is written 3 pages into it; also the glTexImage2D man page is missing this information). It is indeed written at the top of page 67 in the 2.0.24 spec.

> 
> Section 3.7.2 says the level parameter of glCopyTexImage2D is
> interpreted in exactly the same way as the level parameter of
> glTexImage2D. Hence the check for INVALID_VALUE in the test.

Thanks a lot, I had missed that too. (Also, the glCopyTexImage2D man page is missing this information)

> 
> Section 3.7.11 says glGenerateMipmap returns INVALID_OPERATION for
> NPOT
> textures.

Yes, that I had seen.

> 
> What is not clear about this?

Nothing, I guess! Thanks for walking me through these parts of the spec!

> 3.8.2 comes into play if the application has specified a mipmapped
> minification filter or a wrap mode for an NPOT texture. TexParameter
> does not flag an error because the texture image(s) might well be
> changed prior to use in rendering.

Yes, that part I understood.

Thanks,
Benoit

> 
> Regards
> 
> -Mark
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